Ella-Li Spik of Jokkmokk, Sweden, is one of only a small percentage of Sami who grow up herding reindeer. She is part of a new generation with plans to attend college. "I want to explore the world," she says, "but I always want reindeer to be part of my life."

Reindeer can spook suddenly, so Nils Peder kneels calmly in the midst of the herd on which his livelihood depends. He holds a lasso color-coded to indicate the temperature and season in which it works best. As he watches the animals, Nils Peder is yoiking, chanting a throaty, traditional Sami song evoking his wife, Ingrid. The Lutheran pastors who converted the Sami forbade yoiking, calling it devil's music. Nils Peder learned it from his grandparents and has taught it to his children.

The reindeer trudge through deep snow to find food in their winter grazing grounds outside Harrå, Sweden. Lichen is the staple of their winter diet, and they must push aside the snow to reach it. The wetter snow associated with warmer temperatures in recent years causes a frozen crust to form over the plants, which the reindeer can't break through.

Cone-shaped tents called lávut provide temporary shelter for Sami herders while following the reindeer. Nils Peder Gaup, resting here on the tundra, feels most at home in the mountains. "The Sami spirit follows you," he says.

Sven Skaltje makes a meal from some staples of the Sami diet—dried reindeer meat, homemade bread, coffee—in the kitchen of the apartment he shares with five of his siblings in Gällivare, Sweden. They split their time between the town and their village of Harrå, unreachable by roads. Skaltje spends much of the winter on the tundra with his herd. "I feel empty when I am away from the reindeer," he says.

Sven Skaltje was saddened to find the carcasses of two female reindeer whose antlers had become entangled during a dominance struggle in northern Sweden. He estimates it took three days for them to die of starvation. After separating the bodies, he saw from the ear markings that one belonged to him and the other to his cousin. Skaltje is much admired by the younger Sami in his herding group, but he is unsure whether the skills he teaches them will endure.

Frames of lávut are a common sight in Sami yards, where they are used for smoking meat. Sami have long used the tents as portable shelters—their wide bases and forked poles enable them to withstand winds of up to 50 miles an hour on the Arctic tundra. Easy to transport and erect, the frames were originally covered with reindeer skins, but waxed canvas or lightweight woven materials are more common today.

Sara Gaup, 14, is dressed for her confirmation. The garb that she and her father, Nils Peder Gaup, wear identifies their hometown as Kautokeino, Norway. The upturned tips of their reindeer-hide boots were designed to hook into skis.

A reindeer lies slaughtered on a table in the Gaups' modern kitchen in Kautokeino, Norway. Not a bit of it will go to waste. The family freezes, smokes, or dries the meat, as well as the organs, fat, blood, and even hooves. Some Sami make handicrafts using antlers and bones for tools and toys, tendons for thread, and skins for bags and garments. They spend months preparing hides—scraping, soaking, drying, and stretching the leather by hand. To sell meat commercially, herders transport reindeer to slaughterhouses, which butcher the meat and discard the rest.

Mathis Gaup wades into the herd of pounding reindeer to separate the pregnant cows—the ones that still have antlers—from the rest, briefly grasping one reindeer by her leg to guide her outside the stockade. In 2011 only 50 percent of the females bore calves in the Gaup family's herds in Norway, down from the usual 80 percent. But herders take bad years in stride. "Nature controls the size of the herd," says Mathis's brother, Nils Peder.

Calf marking takes place each summer in Norway. After the pregnant reindeer give birth to their calves, the herders briefly separate them from their mothers while a mark—unique to each owner—is notched into the edges of their ears.

SunnaKati Skaltje and her boyfriend, Johan Karlsson, prepare to meet friends and family for the annual Jokkmokk Market in northern Sweden. The gathering attracts hundreds of Sami to its performances and exhibits, reindeer races, and stalls filled with food and handicrafts.

Ingrid Gaup attended boarding school in Sweden before marrying and moving to Norway. She follows the Sami tradition of making some household items herself. She collects "shoe grass" in river marshes, dries and braids it, then shapes it to fit inside winter boots. "It traps warm air and absorbs moisture much better than modern insulation," says Ingrid.

Johan Kuhmunen, with his dog Cammu, lives in Sweden, but the summertime range for his family's herd crosses into Norway. The Sami tradition of learning from the elders is an important part of reindeer herding, and knowledge is passed down from generation to generation and not learned in books.